Carotenoids are the precursors of Vitamin A (required for vision) and are vital in photoprotection of animal and plant cells. The carotenoid biosynthetic pathway is a regulated pathway in plants, yet we have no information on the expression or regulation of specific genes (regulatory or biosynthetic) associated with the pathway. Considering that carotenoids play a significant role in photoprotection and energy transfer, it is compelling to explore the molecular basis of carotenoid biosynthesis and its regulation. Moreover, since this pathway must incorporate numerous regulatory mechanisms, a large contribution to our understanding of gene expression, gene regulation, and signal transduction, is nonexistent. We propose to isolate and characterize genes expressed in maize to begin answering questions regarding regulation of carotenoid biosynthesis in higher plants. An important outgrowth of this research will be the potential for future genetic engineering of carotenoid genes into plants, such as rice, which are nutritionally limited in carotenoids (essential in synthesis of vitamin A and in cancer prevention).